Abstract 1713: TRMT6-mediated N1-methyladenosine methylation promotes tumorigenesis in colorectal cancer
Authors: SILEI SUI, CAIMING XU, Ying Qing, Hideo Baba, Ajay Goel
Journal: Cancer Research (2023)

Abstract Background: N1-methyladenosine (m1A) within tRNAs, an essential and highly conserved RNA modification, has recently emerged as a significant epigenetic modification that plays a pivotal role in tumor progression in some cancers. However, the role of m1A methylation in colorectal cancer (CRC) remains largely unexplored. TRMT6 is the most critical methyltransferase that catalyzes N1-methyladenine modification within tRNA, and early evidence suggests that this TRMT6-mediated m1A methylation is also required for the self-renewal of cancer stem cells (CSCs). Herein, we systematically interrogated the role of TRMT6 in mediating stemness and pathogenesis of CRC. Methods: We first analyzed the expression levels of all m1A regulators in paired tumor and adjacent-normal samples from TCGA and GEO databases. Subsequently, real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blotting (WB) assays were performed to validate the dysregulation of TRMT6 in CRC tissues and cell lines. m1A dot-blot assays were undertaken to detect methylation levels in CRC tissues and RKO and SW620 CRC cell lines. Cell viability, colony formation, spheroid formation, wound healing, and invasion assays were conducted to investigate the biological functions of TRMT6 in CRC. Results: Higher m1A methylation levels were detected in CRC than in normal tissues. By analyzing the expression of ten m1A regulators in public datasets, and subsequent qRT-PCR validation in a CRC clinical cohort, we identified that high TRMT6 expression was significantly associated with advanced tumor stages (III&amp;IV vs. I&amp;II, p&amp;lt;0.05) and poor prognosis (5-year relapse-free survival rates in high vs. low expression groups: 50.9% vs. 65.1%, p&amp;lt;0.05). TRMT6 silencing in CRC cell lines inhibited cell growth, colony formation, and metastatic efficiency (p&amp;lt;0.01-0.001). Furthermore, we discovered that the TRMT6 could enhance stem cell-like properties required for CSC self-renewal. Transcriptomic profiling identified that the epidermal growth factor receptor (EGFR) pathway is one of the critical signaling regulators of TRMT6 in CRC. The TRMT6 knockdown resulted in significant inhibition of p-EGFR and p-ERK, but not p-AKT in CRC cell lines (all p&amp;lt;0.05), which suggested that m1A modification exerts its oncogenic effects in CRC by activating EGFR downstream pathway. Conclusion: Our study elucidates for the first time the oncogenic effects of TRMT6 on catalyzing m1A modification through the EGFR/ERK pathway, which could offer a promising therapeutic strategy in CRC. Citation Format: SILEI SUI, CAIMING XU, Ying Qing, Hideo Baba, Ajay Goel. TRMT6-mediated N1-methyladenosine methylation promotes tumorigenesis in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1713.